Imaging lens

ABSTRACT

There is provided a compact and high-resolution imaging lens at a low cost. 
     The imaging lens comprises in order from an object side to an image side, a first lens having positive refractive power and a convex surface facing the object side near an optical axis, a second lens having negative refractive power and a meniscus shape having the convex surface facing the object side near the optical axis, a third lens having the positive or the negative refractive power, a fourth lens having the convex surface facing the image side near the optical axis, a fifth lens having the positive refractive power, a sixth lens having the positive refractive power, and a seventh lens having the negative refractive power and a concave surface facing the image side near the optical axis, the image side surface of said seventh lens is formed as an aspheric surface which changes to the convex surface at a peripheral area, the object-side surface of said fifth lens has the convex surface facing the object side near the optical axis, all lenses are single lenses arranged with an interval between lenses adjacent to each other, and below conditional expressions (1), (2) and (3) are satisfied: 
       1.50&lt; Nd 1&lt;1.60  (1)
 
       −8.0 f 2/ f &lt;−2.0  (2)
 
       0.3&lt; t 2/ t 3&lt;3.3  (3)
     where   Nd1: refractive index at d-ray of the first lens,   f: focal length of the overall optical system,   f2: focal length of the second lens,   t2: distance along the optical axis from the image-side surface of the second lens to the object-side surface of the third lens, and   t3: distance along the optical axis from the image-side surface of the third lens to the object-side surface of the fourth lens.

The present application is based on and claims priority of a Japanesepatent application No. 2017-196848 filed on Oct. 10, 2017, the entirecontents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an imaging lens which forms an image ofan object on a solid-state image sensor such as a CCD sensor or a C-MOSsensor used in a compact imaging device.

Description of the Related Art

In recent years, it becomes common that camera function is mounted inmany information terminal equipment. It is expected that development ofvarious products with the camera function pursuing convenience andsatisfaction of customers will continue accordingly.

The imaging lens used in such equipment is required to be compact and tohave high-resolution performance, and spread of the imaging lens andreduction in cost are also required.

For Example, as a conventional imaging lens aiming the high-resolutionperformance, the imaging lens disclosed in the following Patent Document1 has been known.

Patent Document 1 (JP2012-155223A) discloses an imaging lens comprising,in order from an object side, a first lens having a biconvex shape, asecond lens having a biconcave shape and being cemented to the firstlens, a third lens having negative refractive power and a meniscus shapehaving a convex surface facing the object side, a fourth lens havingpositive refractive power and the meniscus shape having a concavesurface facing the object side, a fifth lens having the negativerefractive power and the meniscus shape having a convex surface facingthe object side, a sixth lens having the biconvex shape, and a seventhlens having the biconcave shape. In such imaging lens, a front groupcomprises the first lens to the fourth lens and a rear group comprisesthe fifth lens to the seventh lens. The ratio of focal lengths of thefront group to that of the rear group is controlled in a predeterminedrange, therefore proper aberration corrections are realized whilereducing a size of an optical system.

SUMMARY OF THE INVENTION

Regarding the imaging lens having a seven-lens configuration disclosedin the above-described Patent Document 1, F-number is relatively smalland the aberrations are properly corrected, however, sufficientreduction in size is not achieved. Furthermore, the configurationincluding a glass lens or a cemented lens has difficulty inmanufacturing process, and reduction in cost is also difficult.

The present invention has been made in view of the above-describedproblems, and an object of the present invention is to provide animaging lens which is compact and bright, and has high resolution at alow cost.

Regarding terms used in the present invention, a term of a convexsurface, a concave surface or a plane surface of lens surfaces impliesthat a shape of the lens surface near an optical axis (paraxialportion), and a term of refractive power implies the refractive powernear the optical axis. The pole point implies an off-axial point on anaspheric surface at which a tangential plane intersects the optical axisperpendicularly. The total track length is defined as a distance alongthe optical axis from an object-side surface of an optical elementlocated closest to the object to an image plane. The total track lengthand the back focus is determined under a condition that thickness of anIR cut filter or a cover glass which may be arranged between the imaginglens and the image plane is regarded as an air.

An imaging lens according to the present invention comprises in orderfrom an object side to an image side, a first lens having positiverefractive power and a convex surface facing the object side near anoptical axis, a second lens having negative refractive power and ameniscus shape having the convex surface facing the object side near theoptical axis, a third lens having the positive or the negativerefractive power, a fourth lens having the convex surface facing theimage side near the optical axis, a fifth lens having the positiverefractive power, a sixth lens having the positive refractive power, anda seventh lens having the negative refractive power and a concavesurface facing the image side near the optical axis. The image sidesurface of the seventh lens is formed as an aspheric surface whichchanges to the convex surface at a peripheral area. All lenses aresingle lenses arranged with an interval between lenses adjacent to eachother.

In the imaging lens having the above-described configuration, the firstlens, the fifth lens and the sixth lens achieve low-profileness by thepositive refractive power of each lens. The second lens properlycorrects chromatic aberration and spherical aberration occurred at thefirst lens by the negative refractive power. An image-side surface ofthe fourth lens is the convex surface facing the image side near theoptical axis, and therefore the total track length is suppressed to besmall and a light ray incident angle to the fifth lens is madeappropriate. The image-side surface of the seventh lens is the concavesurface facing the image side near the optical axis, and is the asphericsurface having a pole point at an area apart from the optical axis.Therefore, back focus is secured near the optical axis by the negativerefractive power, and the light ray incident angle to the peripheralarea is appropriately controlled. Thereby, field curvature is properlycorrected and the light ray incident angle to an image sensor is madeappropriate. Furthermore, the all lenses are single lenses arranged withintervals therebetween, therefore manufacturing becomes facilitated. Inthe imaging lens having the above-described configuration, it ispreferable that the object-side surface of the fifth lens is the convexsurface facing the object side near the optical axis, and in this case,astigmatism and field curvature can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that a below conditional expression (1) is satisfied:

1.50<Nd1<1.60  (1)

Where

Nd1: refractive index at d-ray of the first lens.

The conditional expression (1) defines an appropriate range of therefractive power at d-ray of the first lens. The range of theconditional expression (1) becomes a condition for selecting aninexpensive plastic material.

According to the imaging lens having the above-described configuration,it is preferable that a below conditional expression (2) is satisfied:

−8.0f2/f<−2.0  (2)

where

f2: focal length of the second lens, and

f: focal length of the overall optical system.

The conditional expression (2) defines an appropriate range of thenegative refractive power of the second lens. By satisfying theconditional expression (2), spherical aberration and the chromaticaberration can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that a below conditional expression (3) is satisfied:

0.3<t2/t3<3.3  (3)

where

t2: distance along the optical axis from the image-side surface of thesecond lens to the object-side surface of the third lens, and

t3: distance along the optical axis from the image-side surface of thethird lens to the object-side surface of the fourth lens.

The conditional expression (3) defines an appropriate ratio of aninterval along the optical axis between the second lens and the thirdlens, and an interval along the optical axis between the third lens andthe fourth lens. By satisfying the conditional expression (3), eachinterval of the lenses becomes appropriate and the total track lengthcan be suppressed to be small.

According to the imaging lens having the above-described configuration,it is preferable that the fourth lens has the negative refractive powernear the optical axis.

The chromatic aberration and the spherical aberration can be properlycorrected by the fourth lens having the negative refractive power.

According to the imaging lens having the above-described configuration,it is preferable that composite refractive power of the fifth lens, thesixth lens and the seventh lens is positive, and more preferable that abelow conditional expression (4) is satisfied:

3.0<f567/f<10.0  (4)

where

f567: composite focal length of the fifth lens, the sixth lens and theseventh lens, and

f: focal length of the overall optical system of the imaging lens.

The conditional expression (4) defines an appropriate range of thecomposite refractive power of the fifth lens, the sixth lens and theseventh lens. When the fifth lens has the positive refractive power, thesixth lens has the positive refractive power and the seventh lens hasthe negative refractive power, and each refractive power of these threelenses is distributed so that the composite refractive power becomespositive, the total track length can be suppressed to be small.Furthermore, by satisfying the conditional expression (4), the fieldcurvature and distortion can be properly corrected while securing backfocus.

According to the imaging lens having the above-described configuration,it is preferable that a below conditional expression (5) is satisfied:

−10.0<(r9+r10)/(r9−r10)<−0.5  (5)

where

r9: paraxial curvature radius of the object-side surface of the fifthlens, and

r10: paraxial curvature radius of the image-side surface of the fifthlens.

The conditional expression (5) defines shapes of the object-side surfaceand the image-side surface of the fifth lens by ratio of paraxialcurvature radii. By satisfying the conditional expression (5), thelow-profileness can be easily achieved, and the distortion, thechromatic aberration, the astigmatism and the field curvature can beproperly corrected.

According to the imaging lens having the above-described configuration,it is preferable that a below conditional expression (6) is satisfied:

1.0<|f23|/f<4.5  (6)

where

f23: composite focal length of the second lens and the third lens, and

f: focal length of the overall optical system of the imaging lens.

The conditional expression (6) defines an appropriate range of thecomposite refractive power of the second lens and the third lens. When avalue is below the upper limit of the conditional expression (6), thechromatic aberration can be properly corrected. On the other hand, whenthe value is above the lower limit of the conditional expression (6),the field curvature and the distortion can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that a below conditional expression (7) is satisfied:

0.01<t3/f<0.15  (7)

where

t3: distance along the optical axis from the image-side surface of thethird lens to the object-side surface of the fourth lens, and

f: focal length of the overall optical system of the imaging lens.

The conditional expression (7) defines an appropriate range of theinterval along the optical axis between the third lens and the fourthlens. By satisfying the conditional expression (7), the total tracklength can be suppressed to be small.

According to the imaging lens having the above-described configuration,it is preferable that below conditional expressions (8) and (9) aresatisfied:

50<νd1<60  (8)

15<νd2<25  (9)

where

νd1: abbe number at d-ray of the first lens, and

νd2: abbe number at d-ray of the second lens.

The conditional expressions (8) and (9) define appropriate ranges of theabbe numbers at d-ray of the first lens and the second lens. Bysatisfying the conditional expressions (8) and (9), axial chromaticaberration can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that below conditional expression (10) is satisfied:

15<νd4<25  (10)

where

νd4: abbe number at d-ray of the fourth lens.

The conditional expression (10) defines an appropriate range of the abbenumbers at d-ray of the fourth lens. By satisfying the conditionalexpression (10), the chromatic aberration of magnification can beproperly corrected.

According to the imaging lens having the above-described configuration,it is preferable that below conditional expressions (11), (12) and (13)are satisfied:

50<νd5<60  (11)

50<νd6<60  (12)

50<νd7<60  (13)

where

νd5: abbe number at d-ray of the fifth lens,

νd6: abbe number at d-ray of the sixth lens, and

νd7: abbe number at d-ray of the seventh lens.

By satisfying the conditional expressions (11), (12) and (13), aninexpensive plastic material can be selected.

According to the imaging lens having the above-described configuration,it is preferable that a below conditional expression (14) is satisfied:

0.05<d1/f<0.30  (14)

where

d1: thickness along the optical axis of the first lens, and

f: focal length of the overall optical system of the imaging lens.

The conditional expression (14) defines an appropriate range of thethickness along the optical axis of the first lens. When a value isbelow the upper limit of the conditional expression (14), the thicknessalong the optical axis of the first lens is prevented from beingexcessively large, and securing the air gap on the image side of thefirst lens is facilitated. Thereby, the low-profileness can bemaintained. On the other hand, when the value is above the lower limitof the conditional expression (14), the thickness along the optical axisof the first lens is prevented from being excessively small, and theformability of the lens is improved.

According to the imaging lens having the above-described configuration,it is preferable that a below conditional expression (15) is satisfied:

1.0<f12/f<3.0  (15)

where

f12: composite focal length of the first lens and the second lens, and

f: focal length of the overall optical system of the imaging lens.

The conditional expression (15) defines an appropriate range of thecomposite refractive power of the first lens and the second lens. When avalue is below the upper limit of the conditional expression (15),positive composite refractive power of the first lens and the secondlens is made appropriate, and the low-profileness can be achieved. Onthe other hand, when the value is above the lower limit of theconditional expression (15), the spherical aberration and comaaberration can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that a below conditional expression (16) is satisfied:

2.5<|f34|/f<12.0  (16)

where

f34: composite focal length of the third lens and the fourth lens, and

f: focal length of the overall optical system of the imaging lens.

The conditional expression (16) defines an appropriate range of thecomposite refractive power of the third lens and the fourth lens. When avalue is below the upper limit of the conditional expression (16), thechromatic aberration can be properly corrected. On the other hand, whenthe value is above the lower limit of the conditional expression (16),the astigmatism and the distortion can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that a below conditional expression (17) is satisfied:

1.7<f5/f<4.5  (17)

where

f5: focal length of the fifth lens, and

f: focal length of the overall optical system.

The conditional expression (17) defines an appropriate range of therefractive power of the fifth lens. When a value is below the upperlimit of the conditional expression (17), the positive refractive powerof the fifth lens becomes appropriate and the low-profileness can beachieved. On the other hand, when the value is above the lower limit ofthe conditional expression (17), the coma aberration, the astigmatismand the distortion can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that a below conditional expression (18) is satisfied:

0.1<r1/r2<0.7  (18)

where

r1: paraxial curvature radius of the object-side surface of the firstlens, and

r2: paraxial curvature radius of the image-side surface of the firstlens.

The conditional expression (18) defines shapes of the object-sidesurface and the image-side surface of the first lens by ratio ofparaxial curvature radii. By satisfying the conditional expression (18),the spherical aberration and the distortion can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that an aperture stop is arranged closer to the objectthan the object side of the second lens.

By arranging the aperture stop closer to the object, an exit pupil canbe located away from an image plane. Thereby, telecentricity of theimage side can be secured and decrease in light quantity at theperipheral area can be suppressed.

According to the imaging lens having the above-described configuration,it is preferable that all lenses from the first lens to the seventh lenshave at least one aspheric surface, respectively, and more preferablethat both surfaces of all lenses from the first lens to the seventh lensare aspheric surfaces.

By using many aspheric surfaces, aberration corrections at theperipheral area can be especially facilitated. Furthermore, it ispreferable that all lenses are made of the plastic material by which theaspheric surfaces can be easily formed. It is also preferable that atleast two lenses of the fifth lens, the sixth lens and the seventh lenshave aspheric surface(s) having at least one pole point on either theobject side or the image side, or both of the object side and the imageside. Such shapes using the aspheric surfaces facilitates the aberrationcorrections at the peripheral area.

Effect of Invention

According to the present invention, there can be provided an imaginglens which is compact and bright, and has high resolution at a low cost.

It is not necessary to satisfy all conditional expressions (1) to (18).By satisfying the conditional expression individually, operationaladvantage corresponding to each conditional expression can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a general configuration of an imaginglens in Example 1 according to the present invention;

FIG. 2 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 1 according to the present invention;

FIG. 3 is a schematic view showing the general configuration of animaging lens in Example 2 according to the present invention;

FIG. 4 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 2 according to the present invention;

FIG. 5 is a schematic view showing the general configuration of animaging lens in Example 3 according to the present invention;

FIG. 6 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 3 according to the present invention;

FIG. 7 is a schematic view showing the general configuration of animaging lens in Example 4 according to the present invention;

FIG. 8 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 4 according to the present invention.

FIG. 9 is a schematic view showing a general configuration of an imaginglens in Example 5 according to the present invention;

FIG. 10 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 5 according to the present invention;

FIG. 11 is a schematic view showing the general configuration of animaging lens in Example 6 according to the present invention;

FIG. 12 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 6 according to the present invention;

FIG. 13 is a schematic view showing the general configuration of animaging lens in Example 7 according to the present invention; and

FIG. 14 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 7 according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, the preferred embodiment of the present invention will bedescribed in detail referring to the accompanying drawings.

FIGS. 1, 3, 5, 7, 9, 11 and 13 are schematic views of the imaging lensesin Examples 1 to 7 according to the embodiments of the presentinvention, respectively.

As shown in FIG. 1, the imaging lens according to the presentembodiments comprises in order from an object side to an image side, afirst lens L1 having positive refractive power and a convex surfacefacing the object side near an optical axis X, a second lens L2 havingnegative refractive power and a meniscus shape having the convex surfacefacing the object side near the optical axis X, a third lens L3 havingthe positive or the negative refractive power, a fourth lens L4 havingthe convex surface facing the image side near the optical axis X, afifth lens L5 having the positive refractive power, a sixth lens L6having the positive refractive power, and a seventh lens L7 having thenegative refractive power and a concave surface facing the image sidenear the optical axis X. The image side surface of the seventh lens L7is formed as an aspheric surface which changes to the convex surface ata peripheral area. All lenses are single lenses arranged with aninterval between lenses adjacent to each other.

A filter IR such as an IR cut filter and a cover glass is arrangedbetween the seventh lens L7 and an image plane IMG (namely, an imageplane of the image sensor). The filter IR is omissible.

An aperture stop STO is arranged between a vertex position of theobject-side surface of the first lens L1 and a periphery of theobject-side surface.

The first lens L1 has the meniscus shape having the convex surfacefacing the object side and the concave surface facing the image sidenear the optical axis X. Therefore, coma aberration, field curvature anddistortion can be properly corrected.

The second lens L2 has the meniscus shape having the convex surfacefacing the object side and the concave surface facing the image sidenear the optical axis X. Therefore, axial chromatic aberration,high-order spherical aberration, the coma aberration and the fieldcurvature can be properly corrected.

The third lens L3 has positive refractive power and a biconvex shapehaving the convex surfaces facing the object side and the image sidenear the optical axis X. The field curvature and the coma aberration canbe properly corrected by aspheric surfaces on both sides. A shape of thethird lens L3 is not limited to the biconvex shape. In the Example shownin FIG. 11, the third lens L3 has the meniscus shape having the convexsurface facing the object side and the concave surface facing the imageside near the optical axis X. In this case, the coma aberration, thefield curvature and the distortion can be properly corrected.Furthermore, the refractive power of the third lens L3 may be negativeas shown in the Example in FIG. 13. In this case, the third lens L3 hasa biconcave shape having the concave surfaces facing the object side andthe image side near the optical axis X, therefore the chromaticaberration can be properly corrected.

The fourth lens L4 has the meniscus shape having the concave surfacefacing the object side and the convex surface facing the image side nearthe optical axis X. The convex surface facing the image side controlslight ray incident angle to the fifth lens L5 to be appropriate, andcontributes to shortening of total track length. Furthermore, the fourthlens L4 has the negative refractive power so as to diverge light rayemitted from the third lens L3 and enter the same into the fifth lensL5. However, also the positive refractive power may be adoptable if anappropriate paraxial curvature radius and the aspheric surface areprovided.

The fifth lens L5 has the meniscus shape having the convex surfacefacing the object side and the concave surface facing the image sidenear the optical axis X, and astigmatism, the field curvature and thedistortion can be properly corrected. The shape of the fifth lens L5 isnot limited to the above-described shape. In the Example shown in FIG.11, the fifth lens L5 has the biconvex shape having the convex surfacesfacing both of object side and the image side near the optical axis X.In this case, the positive refractive power on the both surfaces arefavorable to low-profileness.

The sixth lens L6 has the meniscus shape having the convex surfacefacing the object side and the concave surface facing the image sidenear the optical axis X, and the astigmatism, the field curvature andthe distortion can be properly corrected. The shape of the sixth lens L6is not limited to the above-described shape. In the Examples shown inFIGS. 3, 5, 7, 9, 11 and 13, the sixth lens L6 has the biconvex shapehaving the convex surfaces facing both of the object side and the imageside near the optical axis X. In this case, the positive refractivepower on the both surfaces are favorable to low-profileness.

The seventh lens L7 has the meniscus shape having the convex surfacefacing the object side and the concave surface facing the image sidenear the optical axis X, and the field curvature and the distortion canbe properly corrected. The shape of the seventh lens L7 is not limitedto the above-described shape. In the Examples shown in FIGS. 11 and 13,the seventh lens L7 has the biconcave shape having the concave surfacesfacing both of the object side and the image side near the optical axisX. Such shape is favorable to correction of the chromatic aberration.

The image-side surface of the seventh lens L7 is the aspheric surfacewhich changes to the convex surface at an area apart from the opticalaxis X. Therefore, back focus is secured near the optical axis X by thenegative refractive power, and the light ray incident angle to theperipheral area is appropriately controlled. Thereby, the fieldcurvature can be properly corrected, and the light ray incident angle tothe image sensor is made appropriate.

Regarding the imaging lens according to the present embodiments, it ispreferable that all lenses of the first lens L1 to the seventh lens L7are single lenses which are not cemented each other. Configuration withonly the single lenses can use many aspheric surfaces. In the presentembodiment, all surfaces of the lenses have aspheric surfaces and propercorrection of the aberrations can be realized. Furthermore, incomparison with a case using the cemented lenses, workload for cementingis unnecessary, and manufacturing in low cost becomes available.

Regarding the imaging lens according to the present embodiments, aplastic material is used for all of the lenses, and mass production in alow cost can be realized.

It is preferable that all surfaces of the lenses are aspheric surfaces,however, in accordance with required performance, spherical surfaces maybe used which are manufactured easily.

The imaging lens according to the present embodiments shows preferableeffect by satisfying the below conditional expressions (1) to (18).

1.50<Nd1<1.60  (1)

−8.0<f2/f<−2.0  (2)

0.3<t2/t3<3.3  (3)

3.0<f567/f<10.0  (4)

−10.0<(r9+r10)/(r9−r10)<−0.5  (5)

1.0<|f23|/f<4.5  (6)

0.01<t3/f<0.15  (7)

50<νd1<60  (8)

15<νd2<25  (9)

15<νd4<25  (10)

50<νd5<60  (11)

50<νd6<60  (12)

50<νd7<60  (13)

0.05<d1/f<0.30  (14)

1.0<f12/f<3.0  (15)

2.5<|f34|/f<12.0  (16)

1.7<f5/f<4.5  (17)

0.1<r1/r2<0.7  (18)

where

Nd1: refractive index at d-ray of the first lens L1,

νd1: abbe number at d-ray of the first lens L1,

νd2: abbe number at d-ray of the second lens L2,

νd4: abbe number at d-ray of the fourth lens L4,

νd5: abbe number at d-ray of the fifth lens L5,

νd6: abbe number at d-ray of the sixth lens L6,

νd7: abbe number at d-ray of the seventh lens L7,

t2: distance along the optical axis X from the image-side surface of thesecond lens L2 to the object-side surface of the third lens L3,

t3: distance along the optical axis X from the image-side surface of thethird lens L3 to the object-side surface of the fourth lens L4,

d1: thickness along the optical axis X of the first lens L1,

f: focal length of the overall optical system,

f2: focal length of the second lens L2,

f5: focal length of the fifth lens L5,

f12: composite focal length of the first lens L1 and the second lens L2,

f23: composite focal length of the second lens L2 and the third lens L3,

f34: composite focal length of the third lens L3 and the fourth lens L4,

f567: composite focal length of the fifth lens L5, the sixth lens L6,and the seventh lens L7,

r1: paraxial curvature radius of the object-side surface of the firstlens L1,

r2: paraxial curvature radius of the image-side surface of the firstlens L1,

r9: paraxial curvature radius of the object-side surface of the fifthlens L5, and

r10: paraxial curvature radius of the image-side surface of the fifthlens L5.

The imaging lens according to the present embodiments shows furtherpreferable effect by satisfying the below conditional expressions (1a)to (18a).

1.52<Nd1<1.57  (1a)

−7.1<f2/f<−2.5  (2a)

0.5<t2/t3<3.0  (3a)

3.2<f567/f<7.5  (4a)

−8.7<(r9+r10)/(r9−r10)<−0.7  (5a)

1.5<|f23|/f<3.9  (6a)

0.02<t3/f<0.12  (7a)

53<νd1<58  (8a)

17<νd2<23  (9a)

17<νd4<24  (10a)

53<νd5<58  (11a)

53<νd6<58  (12a)

53<νd7<58  (13a)

0.09<d1/f<0.23  (14a)

1.1<f12/f<2.6  (15a)

3.0<|f34|/f<11.0  (16a)

1.8<f5/f<4.3  (17a)

0.2<r1/r2<0.6  (18a)

The signs in the above conditional expressions have the same meanings asthose in the paragraph before the preceding paragraph.

In this embodiment, the aspheric shapes of the surfaces of the asphericlens are expressed by Equation 1, where Z denotes an axis in the opticalaxis direction, H denotes a height perpendicular to the optical axis, Rdenotes a paraxial curvature radius, k denotes a conic constant, and A4,A6, A8, A10, A12, A14, A16, A18 and A20 denote aspheric surfacecoefficients.

$\begin{matrix}{Z = {\frac{\frac{H^{2}}{R}}{1 + \sqrt{1 - {\left( {k + 1} \right)\frac{H^{2}}{R^{2}}}}} + {A_{4}H^{4}} + {A_{6}H^{6}} + {A_{8}H^{8}} + {A_{10}H^{10}} + {A_{12}H^{12}} + {A_{14}H^{14}} + {A_{16}H^{16}} + {A_{18}H^{18}} + {A_{20}H^{20}}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

Next, examples of the imaging lens according to this embodiment will beexplained. In each example, f denotes the focal length of the overalloptical system of the imaging lens, Fno denotes a F-number, w denotes ahalf field of view, ih denotes a maximum image height, and TTL denotestotal track length. Additionally, i denotes surface number counted fromthe object side, r denotes a curvature radius, d denotes the distance oflenses along the optical axis (surface distance), Nd denotes arefractive index at d-ray (reference wavelength), and νd denotes an abbenumber at d-ray. As for aspheric surfaces, an asterisk (*) is addedafter surface number i.

Example 1

The basic lens data is shown below in Table 1.

TABLE 1 Unit mm f = 4.79 ih = 4.03 Fno = 1.70 TTL = 6.20 ω(°) = 39.5Surface Data Surface Curvature Surface Refractive Abbe Focal Number iRadius r Distance d Index Nd Number νd Length (Object) Infinity Infinity 1 (Stop) Infinity −0.3625  2* 2.3112 (r1) 0.6767 (d1) 1.5445 (Nd1)55.98 (νd1) 6.62 (=f1)  3* 5.7779 (r2) 0.2821 (t1)  4* 3.4809 (r3)0.2720 (d2) 1.6612 (Nd2) 20.37 (νd2) −14.46 (=f2)  5* 2.4726 (r4) 0.2866(t2)  6* 5.1708 (r5) 0.7032 (d3) 1.5445 (Nd3) 55.98 (νd3) 6.15 (=f3)  7*−9.0345 (r6) 0.4197 (t3)  8* −1.4464 (r7) 0.4000 (d4) 1.6397 (Nd4) 23.53(νd4) −8.00 (=f4)  9* −2.2335 (r8) 0.0550 (t4) 10* 1.9035 (r9) 0.4700(d5) 1.5445 (Nd5) 55.98 (νd5) 9.01 (=f5) 11* 2.8398 (r10) 0.2231 (t5)12* 7.0077 (r11) 0.4600 (d6) 1.5445 (Nd6) 55.98 (νd6) 126.06 (=f6) 13*7.6239 (r12) 0.4079 (t6) 14* 2.4638 (r13) 0.4850 (d7) 1.5348 (Nd7) 55.66(νd7) −11.02 (=f7) 15* 1.6183 (r14) 0.2788 16 Infinity 0.2100 1.563051.30 17 Infinity 0.6462 (Image Plane) Infinity Lens group dataComposite Focal Length Entrance Pupil Diameter 1st lens-2nd lens 10.14(=f12) 2.810 (=EPD) 2nd lens-3rd lens 10.68 (=f23) 3rd lens-4th lens24.47 (=f34) 6th lens-7th lens −12.57 (=f67) 5th lens-6th lens-7th lens16.20 (=f567) Aspheric Surface Data Second Surface Third Surface FourthSurface Fifth Surface Sixth Surface k 0.00000E+00 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 A4 −6.44925E−03  −3.15088E−02 −1.12990E−01  −1.05741E−01  −1.72562E−02  A6 8.35016E−03 2.96526E−033.42630E−02 3.43900E−02 4.57500E−03 A8 −1.30742E−02  −2.70734E−03 1.10201E−03 1.66736E−04 −2.01691E−02  A10 7.06688E−03 −9.00808E−04 −5.05284E−03  −1.88722E−03  1.69965E−02 A12 −2.07377E−03  1.31549E−042.52716E−03 8.53673E−04 −8.27479E−03  A14 0.00000E+00 0.00000E+00−3.52338E−04  0.00000E+00 1.72912E−03 A16 0.00000E+00 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 A18 0.00000E+00 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 A20 0.00000E+00 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 Seventh Surface Eighth Surface NinthSurface Tenth Surface Eleventh Surface k 0.00000E+00 −1.24388E+00 0.00000E+00 −2.99575E+00 0.00000E+00 A4 −3.09171E−03  1.14207E−011.14402E−02 −4.51921E−02 3.75115E−02 A6 −6.05278E−03  −1.33794E−01 −1.68913E−02   1.27425E−02 −8.93125E−02  A8 6.37976E−03 1.26001E−013.04889E−02 −1.14498E−02 6.11237E−02 A10 −6.75940E−03  −6.91414E−02 −1.77244E−02   9.43589E−03 −2.71937E−02  A12 2.38736E−03 2.24296E−025.67614E−03 −6.02375E−03 7.81777E−03 A14 −2.73936E−04  −3.86648E−03 −1.02436E−03   2.34135E−03 −1.41309E−03  A16 0.00000E+00 2.62107E−047.87612E−05 −5.34600E−04 1.53366E−04 A18 0.00000E+00 0.00000E+000.00000E+00  6.61723E−05 −9.06759E−06  A20 0.00000E+00 0.00000E+000.00000E+00 −3.38613E−06 2.22988E−07 Twelfth Surface Thirteenth SurfaceFourteenth Surface Fifteenth Surface k −1.00000E+00 −1.00000E+00−2.16357E+00 −3.69547E+00 A4  3.00581E−02  1.62215E−02 −1.37743E−01−9.59832E−02 A6 −4.61935E−02 −1.19626E−02  6.04107E−02  4.68604E−02 A8 2.26465E−02 −1.50505E−04 −1.93712E−02 −1.75660E−02 A10 −6.82023E−03 2.09493E−03  3.95729E−03  4.53945E−03 A12  1.50806E−03 −8.24287E−04−4.60426E−04 −8.09218E−04 A14 −2.48159E−04  1.57775E−04  2.77135E−05 9.65196E−05 A16  2.71379E−05 −1.67370E−05 −6.71679E−07 −7.20997E−06 A18−1.67605E−06  9.38069E−07 −2.68612E−11  3.01152E−07 A20  4.34054E−08−2.16239E−08  2.50000E−15 −5.33533E−09

The imaging lens in Example 1 satisfies conditional expressions (1) to(18) as shown in Table 8.

FIG. 2 shows spherical aberration (mm), astigmatism (mm), and distortion(%) of the imaging lens in Example 1. The spherical aberration diagramshows the amount of aberration at wavelengths of F-ray (486 nm), d-ray(588 nm), and C-ray (656 nm). The astigmatism diagram shows the amountof aberration at d-ray on a sagittal image surface S (solid line) and ontangential image surface T (broken line), respectively (same as FIGS. 4,6, 8, 10, 12 and 14). As shown in FIG. 2, each aberration is correctedexcellently.

Example 2

The basic lens data is shown below in Table 2.

TABLE 2 Unit mm f = 4.88 ih = 4.03 Fno = 1.70 TTL = 6.20 ω(°) = 39.1Surface Data Surface Curvature Surface Refractive Abbe Focal Number iRadius r Distance d Index Nd Number νd Length (Object) Infinity Infinity 1 (Stop) Infinity −0.4150  2* 2.3033 (r1) 0.7070 (d1) 1.5445 (Nd1)55.98 (νd1) 6.86 (=f1)  3* 5.3516 (r2) 0.1782 (t1)  4* 3.3985 (r3)0.2721 (d2) 1.6709 (Nd2) 19.48 (νd2) −24.87 (=f2)  5* 2.7326 (r4) 0.3239(t2)  6* 5.8363 (r5) 0.6605 (d3) 1.5445 (Nd3) 55.98 (νd3) 7.16 (=f3)  7*−11.2520 (r6) 0.3962 (t3)  8* −1.5256 (r7) 0.4000 (d4) 1.6612 (Nd4)20.37 (νd4) −8.93 (=f4)  9* −2.2715 (r8) 0.0550 (t4) 10* 1.9695 (r9)0.4933 (d5) 1.5445 (Nd5) 55.98 (νd5) 11.75 (=f5) 11* 2.5938 (r10) 0.5193(t5) 12* 10.3411 (r11) 0.4800 (d6) 1.5348 (Nd6) 55.66 (νd6) 11.82 (=f6)13* −16.0000 (r12) 0.0500 (t6) 14* 3.4484 (r13) 0.5009 (d7) 1.5348 (Nd7)55.66 (νd7) −6.14 (=f7) 15* 1.5973 (r14) 0.2488 16 Infinity 0.21001.5630 51.30 17 Infinity 0.7766 (Image Plane) Infinity Lens group dataComposite Focal Length Entrance Pupil Diameter 1st lens-2nd lens 8.57(=f12) 2.865 (=EPD) 2nd lens-3rd lens 10.24 (=f23) 3rd lens-4th lens34.85 (=f34) 6th lens-7th lens −15.24 (=f67) 5th lens-6th lens-7th lens24.11 (=f567) Aspheric Surface Data Second Surface Third Surface FourthSurface Fifth Surface Sixth Surface k 0.00000E+00 0.00000E+000.00000E+00  1.99356E−01 0.00000E+00 A4 −5.51218E−03  −4.43784E−02 −1.10653E−01  −9.75291E−02 −1.78967E−02  A6 9.33360E−03 1.23807E−032.00705E−03  7.19159E−03 −2.04806E−02  A8 −1.39167E−02  1.26112E−024.54758E−02  1.64384E−02 −1.00465E−03  A10 8.20096E−03 −1.49777E−02 −3.63730E−02  −4.93712E−03 4.16960E−03 A12 −2.50334E−03  6.12738E−031.41495E−02 −1.88708E−03 −6.60084E−03  A14 7.96034E−05 −9.63092E−04 −2.06053E−03   1.22912E−03 2.54724E−03 A16 0.00000E+00 0.00000E+000.00000E+00  0.00000E+00 0.00000E+00 A18 0.00000E+00 0.00000E+000.00000E+00  0.00000E+00 0.00000E+00 A20 0.00000E+00 0.00000E+000.00000E+00  0.00000E+00 0.00000E+00 Seventh Surface Eighth SurfaceNinth Surface Tenth Surface Eleventh Surface k 0.00000E+00 −9.66096E−01 0.00000E+00 −3.55046E+00 0.00000E+00 A4 −3.65479E−03  1.00253E−01−1.22736E−02  −1.01118E−01 −5.55963E−02  A6 −3.43083E−02  −1.42612E−01 9.61540E−03  1.04080E−01 2.02861E−02 A8 2.91821E−02 1.38664E−015.23184E−03 −1.02955E−01 −1.53156E−02  A10 −2.57634E−02  −7.33209E−02 1.79563E−04  7.42956E−02 6.75810E−03 A12 1.02836E−02 2.12861E−02−2.49854E−04  −3.89882E−02 −1.90908E−03  A14 −1.37476E−03  −2.86457E−03 −3.18128E−04   1.39668E−02 3.48198E−04 A16 0.00000E+00 8.22034E−059.66892E−05 −3.17444E−03 −4.15639E−05  A18 0.00000E+00 0.00000E+000.00000E+00  4.04071E−04 3.10546E−06 A20 0.00000E+00 0.00000E+000.00000E+00 −2.15562E−05 −1.13160E−07  Twelfth Surface ThirteenthSurface Fourteenth Surface Fifteenth Surface k 0.00000E+00 0.00000E+000.00000E+00 −6.47731E+00 A4 9.77159E−03 1.46787E−01 −6.30931E−02 −5.85692E−02 A6 −1.80178E−02  −1.08337E−01  1.09607E−02  2.23407E−02 A83.15284E−03 4.70621E−02 −1.86861E−03  −8.19644E−03 A10 −2.38894E−04 −1.47020E−02  2.35922E−04  2.13178E−03 A12 1.13969E−05 3.26214E−03−1.85905E−05  −3.76188E−04 A14 −1.27420E−07  −4.96823E−04  8.09661E−07 4.50090E−05 A16 3.36806E−09 4.86769E−05 −1.22753E−08  −3.48251E−06 A18−1.54370E−11  −2.72204E−06  1.76872E−10  1.55030E−07 A20 −2.63746E−10 6.53524E−08 −4.00302E−11  −2.97539E−09

The imaging lens in Example 2 satisfies conditional expressions (1) to(18) as shown in Table 8.

FIG. 4 shows spherical aberration (mm), astigmatism (mm), and distortion(%) of the imaging lens in Example 2. As shown in FIG. 4, eachaberration is corrected excellently.

Example 3

The basic lens data is shown below in Table 3.

TABLE 3 Unit mm f = 4.90 ih = 4.03 Fno = 1.70 TTL = 6.20 ω(°) = 38.9Surface Data Surface Curvature Surface Refractive Abbe Focal Number iRadius r Distance d Index Nd Number νd Length (Object) Infinity Infinity 1 (Stop) Infinity −0.4350  2* 2.2617 (r1) 0.7274 (d1) 1.5445 (Nd1)55.98 (νd1) 6.62 (=f1)  3* 5.3795 (r2) 0.1796 (t1)  4* 3.6532 (r3)0.2720 (d2) 1.6709 (Nd2) 19.48 (νd2) −22.85 (=f2)  5* 2.8619 (r4) 0.3243(t2)  6* 5.6975 (r5) 0.6303 (d3) 1.5445 (Nd3) 55.98 (νd3) 7.35 (=f3)  7*−12.9039 (r6) 0.3866 (t3)  8* −1.4840 (r7) 0.4000 (d4) 1.6612 (Nd4)20.37 (νd4) −8.62 (=f4)  9* −2.2216 (r8) 0.0559 (t4) 10* 1.9158 (r9)0.4706 (d5) 1.5445 (Nd5) 55.98 (νd5) 11.19 (=f5) 11* 2.5525 (r10) 0.5688(t5) 12* 9.1813 (r11) 0.4800 (d6) 1.5348 (Nd6) 55.66 (νd6) 11.32 (=f6)13* −17.4581 (r12) 0.0599 (t6) 14* 3.8367 (r13) 0.4926 (d7) 1.5348 (Nd7)55.66 (νd7) −6.06 (=f7) 15* 1.6781 (r14) 0.2371 16 Infinity 0.21001.5630 51.30 17 Infinity 0.7757 (Image Plane) Infinity Lens group dataComposite Focal Length Entrance Pupil Diameter 1st lens-2nd lens 8.39(=f12) 2.880 (=EPD) 2nd lens-3rd lens 10.99 (=f23) 3rd lens-4th lens47.62 (=f34) 6th lens-7th lens −15.67 (=f67) 5th lens-6th lens-7th lens20.83 (=f567) Aspheric Surface Data Second Surface Third Surface FourthSurface Fifth Surface Sixth Surface k 0.00000E+00 0.00000E+000.00000E+00  1.64513E−01 0.00000E+00 A4 −4.50982E−03  −4.24610E−02 −1.09811E−01  −9.87668E−02 −2.21303E−02  A6 8.96388E−03 1.05408E−032.51846E−03  7.73981E−03 −2.08537E−02  A8 −1.35393E−02  1.20439E−024.53984E−02  1.67578E−02 −2.07184E−03  A10 8.27768E−03 −1.50096E−02 −3.64719E−02  −5.19413E−03 4.01165E−03 A12 −2.58367E−03  6.24365E−031.41098E−02 −1.78655E−03 −6.89583E−03  A14 8.30965E−05 −9.69320E−04 −1.97978E−03   1.17603E−03 2.64817E−03 A16 0.00000E+00 0.00000E+000.00000E+00  0.00000E+00 0.00000E+00 A18 0.00000E+00 0.00000E+000.00000E+00  0.00000E+00 0.00000E+00 A20 0.00000E+00 0.00000E+000.00000E+00  0.00000E+00 0.00000E+00 Seventh Surface Eighth SurfaceNinth Surface Tenth Surface Eleventh Surface k 0.00000E+00 −9.43592E−01 0.00000E+00 −3.26097E+00 0.00000E+00 A4 −6.22316E−03  9.10504E−02−1.62359E−02  −9.40186E−02 −4.53718E−02  A6 −3.54172E−02  −1.26755E−01 1.86572E−02  9.18402E−02 3.36853E−03 A8 2.90110E−02 1.12307E−01−9.76528E−03  −9.12871E−02 −4.98738E−03  A10 −2.59564E−02  −4.35073E−02 1.52277E−02  6.46391E−02 3.36269E−03 A12 1.02339E−02 3.27665E−03−7.78604E−03  −3.21445E−02 −1.35374E−03  A14 −1.29921E−03  2.52489E−031.50510E−03  1.07100E−02 3.30495E−04 A16 0.00000E+00 −5.51209E−04 −7.32454E−05  −2.26157E−03 −5.05055E−05  A18 0.00000E+00 0.00000E+000.00000E+00  2.69515E−04 4.58604E−06 A20 0.00000E+00 0.00000E+000.00000E+00 −1.35719E−05 −1.90887E−07  Twelfth Surface ThirteenthSurface Fourteenth Surface Fifteenth Surface k 0.00000E+00 0.00000E+000.00000E+00 −6.64629E+00 A4 6.29581E−03 1.27788E−01 −6.20042E−02 −5.84041E−02 A6 −1.82959E−02  −9.20581E−02  1.09993E−02  2.26057E−02 A83.15951E−03 3.79155E−02 −1.86557E−03  −9.18094E−03 A10 −2.34942E−04 −1.13854E−02  2.36367E−04  2.77137E−03 A12 1.17911E−05 2.45544E−03−1.85460E−05  −5.70063E−04 A14 −1.05134E−07  −3.64082E−04  8.12435E−07 7.70484E−05 A16 1.01375E−08 3.46286E−05 −1.20139E−08  −6.46076E−06 A182.95151E−10 −1.87660E−06  1.97982E−10  3.01701E−07 A20 −4.12116E−10 4.37855E−08 −4.06314E−11  −5.95676E−09

The imaging lens in Example 3 satisfies conditional expressions (1) to(18) as shown in Table 8.

FIG. 6 shows spherical aberration (mm), astigmatism (mm), and distortion(%) of the imaging lens in Example 3. As shown in FIG. 6, eachaberration is corrected excellently.

Example 4

The basic lens data is shown below in Table 4.

TABLE 4 Unit mm f = 4.81 ih = 4.03 Fno = 1.70 TTL = 6.20 ω(°) = 39.4Surface Data Surface Curvature Surface Refractive Abbe Focal Number iRadius r Distance d Index Nd Number νd Length (Object) Infinity Infinity 1 (Stop) Infinity −0.3550 (d1)  2* 2.4118 (r1) 0.6486 (t1) 1.5445 (Nd1)55.98 (νd1) 6.86 (=f1)  3* 6.1650 (r2) 0.2042 (d2)  4* 3.3506 (r3)0.2500 (t2) 1.6612 (Nd2) 20.37 (νd2) −21.65 (=f2)  5* 2.6345 (r4) 0.3751(d3)  6* 6.1259 (r5) 0.6772 (t3) 1.5445 (Nd3) 55.98 (νd3) 7.15 (=f3)  7*−10.2539 (r6) 0.4003 (d4)  8* −1.4727 (r7) 0.3893 (t4) 1.6709 (Nd4)19.48 (νd4) −8.93 (=f4)  9* −2.1604 (r8) 0.0550 (d5) 10* 1.9259 (r9)0.4509 (t5) 1.5445 (Nd5) 55.98 (νd5) 11.34 (=f5) 11* 2.5681 (r10) 0.4945(d6) 12* 5.9513 (r11) 0.4500 (t6) 1.5348 (Nd6) 55.66 (νd6) 8.30 (=f6)13* −17.0389 (r12) 0.2130 (d7) 14* 4.2200 (r13) 0.4490 1.5348 (Nd7)55.66 (νd7) −4.92 (=f7) 15* 1.5606 (r14) 0.2262 16 Infinity 0.21001.5630 51.30 17 Infinity 0.7791 (Image Plane) Infinity Lens group dataComposite Focal Length Entrance Pupil Diameter 1st lens-2nd lens 9.02(=f12) 2.820 (=EPD) 2nd lens-3rd lens 10.74 (=f23) 3rd lens-4th lens35.21 (=f34) 6th lens-7th lens −16.62 (=f67) 5th lens-6th lens-7th lens19.01 (=f567) Aspheric Surface Data Second Surface Third Surface FourthSurface Fifth Surface Sixth Surface k 0.00000E+00 0.00000E+000.00000E+00  0.00000E+00 0.00000E+00 A4 −5.12156E−03  −3.91898E−02 −1.17539E−01  −1.06661E−01 −2.41304E−02  A6 8.14997E−03 1.78414E−031.09658E−02  1.01744E−02 −1.92635E−02  A8 −1.35640E−02  1.19800E−024.78132E−02  3.53407E−02 4.67371E−03 A10 8.23110E−03 −1.50224E−02 −4.60228E−02  −3.20716E−02 −4.74448E−03  A12 −2.61986E−03  6.26251E−032.02954E−02  1.32382E−02 −6.87516E−04  A14 9.68060E−05 −1.02142E−03 −3.33101E−03  −1.71338E−03 1.20427E−03 A16 0.00000E+00 0.00000E+000.00000E+00  0.00000E+00 0.00000E+00 A18 0.00000E+00 0.00000E+000.00000E+00  0.00000E+00 0.00000E+00 A20 0.00000E+00 0.00000E+000.00000E+00  0.00000E+00 0.00000E+00 Seventh Surface Eighth SurfaceNinth Surface Tenth Surface Eleventh Surface k 0.00000E+00 −1.00617E+00 0.00000E+00 −2.92961E+00 0.00000E+00 A4 −1.92927E−02  8.95765E−026.81643E−03 −7.29819E−02 −2.37989E−02  A6 −1.56585E−02  −9.74797E−02 1.12799E−03  6.12415E−02 −3.92616E−02  A8 −3.50175E−03  4.38010E−02−1.05741E−02  −7.32214E−02 2.82706E−02 A10 2.75016E−03 2.10198E−022.31412E−02  6.44717E−02 −1.07254E−02  A12 −4.53028E−04  −2.62247E−02 −1.27758E−02  −3.70182E−02 2.34535E−03 A14 9.90835E−05 8.95638E−032.82240E−03  1.33201E−02 −3.28090E−04  A16 0.00000E+00 −1.05039E−03 −2.02537E−04  −2.91132E−03 3.45760E−05 A18 0.00000E+00 0.00000E+000.00000E+00  3.50510E−04 −2.89978E−06  A20 0.00000E+00 0.00000E+000.00000E+00 −1.76301E−05 1.27800E−07 Twelfth Surface Thirteenth SurfaceFourteenth Surface Fifteenth Surface k 0.00000E+00 0.00000E+000.00000E+00 −5.76454E+00 A4 6.94900E−02 1.73757E−01 −1.02228E−01 −8.22692E−02 A6 −7.85992E−02  −1.36784E−01  1.87516E−02  3.13008E−02 A82.59756E−02 5.29535E−02 1.25493E−03 −9.31168E−03 A10 −5.54638E−03 −1.23795E−02  1.08148E−04  2.28338E−03 A12 9.15024E−04 1.86262E−03−5.40722E−04  −4.44826E−04 A14 −9.54053E−05  −1.91332E−04  1.63223E−04 6.01902E−05 A16 2.51485E−06 1.38935E−05 −2.13107E−05  −5.00878E−06 A184.60490E−07 −6.67046E−07  1.33221E−06  2.26180E−07 A20 −3.16068E−08 1.56197E−08 −3.26525E−08  −4.21474E−09

The imaging lens in Example 4 satisfies conditional expressions (1) to(18) as shown in Table 8.

FIG. 8 shows spherical aberration (mm), astigmatism (mm), and distortion(%) of the imaging lens in Example 4. As shown in FIG. 8, eachaberration is corrected excellently.

Example 5

The basic lens data is shown below in Table 5.

TABLE 5 Unit mm f = 4.80 ih = 4.03 Fno = 1.60 TTL = 6.20 ω(°) = 39.5Surface Data Surface Curvature Surface Refractive Abbe Focal Number iRadius r Distance d Index Nd Number νd Length (Object) Infinity Infinity 1 (Stop) Infinity −0.4200  2* 2.4027 (r1) 0.7104 (d1) 1.5445 (Nd1)55.98 (νd1) 6.96 (=f1)  3* 5.8877 (r2) 0.1777 (t1)  4* 3.2654 (r3)0.2500 (d2) 1.6612 (Nd2) 20.37 (νd2) −22.87 (=f2)  5* 2.6036 (r4) 0.3892(t2)  6* 5.2911 (r5) 0.6623 (d3) 1.5445 (Nd3) 55.98 (νd3) 7.50 (=f3)  7*−17.0715 (r6) 0.3967 (t3)  8* −1.5442 (r7) 0.3877 (d4) 1.6709 (Nd4)19.48 (νd4) −9.41 (=f4)  9* −2.2503 (r8) 0.0550 (t4) 10* 2.0172 (r9)0.4508 (d5) 1.5445 (Nd5) 55.98 (νd5) 12.48 (=f5) 11* 2.6426 (r10) 0.4346(t5) 12* 5.5114 (r11) 0.4506 (d6) 1.5348 (Nd6) 55.66 (νd6) 6.71 (=f6)13* −10.0000 (r12) 0.2412 (t6) 14* 6.2924 (r13) 0.4516 (d7) 1.5348 (Nd7)55.66 (νd7) −4.52 (=f7) 15* 1.7017 (r14) 0.2272 16 Infinity 0.21001.5630 51.30 17 Infinity 0.7766 (Image Plane) Infinity Lens group dataComposite Focal Length Entrance Pupil Diameter 1st lens-2nd lens 8.99(=f12) 2.995 (=EPD) 2nd lens-3rd lens 11.30 (=f23) 3rd lens-4th lens35.44 (=f34) 6th lens-7th lens −22.53 (=f67) 5th lens-6th lens-7th lens17.79 (=f567) Aspheric Surface Data Second Surface Third Surface FourthSurface Fifth Surface Sixth Surface k 0.00000E+00 0.00000E+000.00000E+00  0.00000E+00 0.00000E+00 A4 −4.47779E−03  −3.52115E−02 −1.07425E−01  −9.87908E−02 −2.29150E−02  A6 7.62599E−03 1.30631E−038.95933E−03  9.04076E−03 −1.66584E−02  A8 −1.10136E−02  9.11361E−033.86217E−02  2.88768E−02 4.00317E−03 A10 6.19686E−03 −1.16121E−02 −3.53514E−02  −2.45315E−02 −3.60859E−03  A12 −1.91101E−03  4.57645E−031.45996E−02  9.53472E−03 −5.60718E−04  A14 8.02824E−05 −6.67663E−04 −2.19206E−03  −1.17908E−03 8.04740E−04 A16 0.00000E+00 0.00000E+000.00000E+00  0.00000E+00 0.00000E+00 A18 0.00000E+00 0.00000E+000.00000E+00  0.00000E+00 0.00000E+00 A20 0.00000E+00 0.00000E+000.00000E+00  0.00000E+00 0.00000E+00 Seventh Surface Eighth SurfaceNinth Surface Tenth Surface Eleventh Surface k 0.00000E+00 −1.00824E+00 0.00000E+00 −3.06003E+00 0.00000E+00 A4 −1.68277E−02  7.47843E−024.36907E−03 −6.25750E−02 −2.50164E−02  A6 −1.37744E−02  −7.58035E−02 2.94338E−04  4.99842E−02 −2.70916E−02  A8 −3.15625E−03  2.70454E−02−9.08948E−03  −5.56343E−02 1.65323E−02 A10 2.11154E−03 2.52522E−022.09049E−02  4.50721E−02 −4.66243E−03  A12 −3.04856E−04  −2.43289E−02 −1.13854E−02  −2.39163E−02 3.97689E−04 A14 6.88405E−05 7.61017E−032.49410E−03  7.95143E−03 9.76742E−05 A16 0.00000E+00 −8.41656E−04 −1.84534E−04  −1.60464E−03 −2.85724E−05  A18 0.00000E+00 0.00000E+000.00000E+00  1.78472E−04 2.76114E−06 A20 0.00000E+00 0.00000E+000.00000E+00 −8.30090E−06 −9.69973E−08  Twelfth Surface ThirteenthSurface Fourteenth Surface Fifteenth Surface k 0.00000E+00 0.00000E+000.00000E+00 −6.83221E+00 A4 5.81143E−02 1.66942E−01 −7.73074E−02 −6.35514E−02 A6 −6.40921E−02  −1.20423E−01  1.45995E−02  2.24500E−02 A81.97058E−02 4.57261E−02 8.53031E−04 −6.04860E−03 A10 −3.87917E−03 −1.08615E−02  6.66940E−05  1.19326E−03 A12 5.91158E−04 1.75514E−03−3.13163E−04  −1.83729E−04 A14 −5.69550E−05  −2.06695E−04  8.55994E−05 2.15098E−05 A16 1.38356E−06 1.76079E−05 −1.01178E−05  −1.66888E−06 A182.34378E−07 −9.50831E−07  5.72883E−07  7.22346E−08 A20 −1.48578E−08 2.34729E−08 −1.27217E−08  −1.29091E−09

The imaging lens in Example 5 satisfies conditional expressions (1) to(18) as shown in Table 8.

FIG. 10 shows spherical aberration (mm), astigmatism (mm), anddistortion (%) of the imaging lens in Example 5. As shown in FIG. 10,each aberration is corrected excellently.

Example 6

The basic lens data is shown below in Table 6.

TABLE 6 Unit mm f = 4.76 ih = 4.03 Fno = 1.51 TTL = 6.33 ω(°) = 39.7Surface Data Surface Curvature Surface Refractive Abbe Focal Number iRadius r Distance d Index Nd Number νd Length (Object) Infinity Infinity 1 (Stop) Infinity −0.4800  2* 2.5106 (r1) 0.7282 (d1) 1.5445 (Nd1)55.98 (νd1) 8.35 (=f1)  3* 5.0334 (r2) 0.0725 (t1)  4* 3.2143 (r3)0.2400 (d2) 1.6612 (Nd2) 20.37 (νd2) −29.72 (=f2)  5* 2.6803 (r4) 0.3412(t2)  6* 4.1440 (r5) 0.5579 (d3) 1.5445 (Nd3) 55.98 (νd3) 8.56 (=f3)  7*35.6203 (r6) 0.4372 (t3)  8* −1.8938 (r7) 0.3300 (d4) 1.6709 (Nd4) 19.48(νd4) −12.94 (=f4)  9* −2.5916 (r8) 0.0400 (t4) 10* 6.0411 (r9) 0.7893(d5) 1.5445 (Nd5) 55.98 (νd5) 10.42 (=f5) 11* −88.8888 (r10) 0.5085 (t5)12* 5.2246 (r11) 0.4852 (d6) 1.5348 (Nd6) 55.66 (νd6) 5.15 (=f6) 13*−5.6427 (r12) 0.4922 (t6) 14* −8.3712 (r13) 0.3800 (d7) 1.5348 (Nd7)55.66 (νd7) −2.98 (=f7) 15* 2.0032 (r14) 0.2178 16 Infinity 0.21001.5630 51.30 17 Infinity 0.5724 (Image Plane) Infinity Lens group dataComposite Focal Length Entrance Pupil Diameter 1st lens-2nd lens 10.63(=f12) 3.160 (=EPD) 2nd lens-3rd lens 12.37 (=f23) 3rd lens-4th lens24.26 (=f34) 6th lens-7th lens −11.72 (=f67) 5th lens-6th lens-7th lens21.03 (=f567) Aspheric Surface Data Second Surface Third Surface FourthSurface Fifth Surface Sixth Surface k 0.00000E+00 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 A4 4.35661E−04 −3.95737E−02 −1.08053E−01  −9.49601E−02  −3.94310E−02  A6 7.94662E−03 2.82931E−031.55161E−02 6.86141E−03 −1.84681E−02  A8 −1.20494E−02  1.20567E−023.07455E−02 3.23083E−02 9.71281E−03 A10 8.09778E−03 −1.49855E−02 −3.00313E−02  −2.53207E−02  −1.11743E−02  A12 −2.67205E−03  6.36641E−031.24791E−02 9.15446E−03 5.88492E−03 A14 2.49876E−04 −9.50473E−04 −1.82325E−03  −1.04352E−03  −9.18909E−04  A16 0.00000E+00 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 A18 0.00000E+00 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 A20 0.00000E+00 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 Seventh Surface Eighth Surface NinthSurface Tenth Surface Eleventh Surface k 0.00000E+00 −6.31395E−01 0.00000E+00 5.34484E+00 0.00000E+00 A4 −2.38915E−02  7.26870E−026.81523E−02 −3.19876E−02  −3.88509E−02  A6 −2.38830E−02  −7.22889E−02 −7.84455E−02  −2.49958E−02  −1.52928E−02  A8 2.52203E−03 4.15706E−027.02456E−02 3.20297E−02 1.60519E−02 A10 −1.95772E−03  −1.11050E−02 −3.53539E−02  −1.95562E−02  −7.25964E−03  A12 3.08049E−03 1.96124E−031.03258E−02 5.77135E−03 1.63392E−03 A14 −7.86913E−04  −5.95699E−04 −1.73158E−03  −8.14900E−04  −1.71303E−04  A16 0.00000E+00 1.19044E−041.40042E−04 4.51489E−05 6.64202E−06 A18 0.00000E+00 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 A20 0.00000E+00 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 Twelfth Surface Thirteenth SurfaceFourteenth Surface Fifteenth Surface k −9.27766E−01  0.00000E+000.00000E+00 −7.67567E+00  A4 6.08419E−02 1.46101E−01 −5.74338E−02 −5.17823E−02  A6 −6.41421E−02  −8.42042E−02  −3.94004E−03  1.42476E−02A8 2.76620E−02 2.38245E−02 7.94277E−03 −2.14860E−03  A10 −9.91470E−03 −4.87384E−03  −1.86828E−03  1.63861E−04 A12 2.20501E−03 6.58142E−042.01977E−04 −5.10399E−06  A14 −2.61909E−04  −5.52377E−05  −1.08369E−05 −1.13326E−08  A16 1.26923E−05 1.94732E−06 2.34039E−07 2.53578E−09 A180.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 A20 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00

The imaging lens in Example 6 satisfies conditional expressions (1) to(18) as shown in Table 8.

FIG. 12 shows spherical aberration (mm), astigmatism (mm), anddistortion (%) of the imaging lens in Example 6. As shown in FIG. 12,each aberration is corrected excellently.

Example 7

The basic lens data is shown below in Table 7.

TABLE 7 Unit mm f = 4.44 ih = 3.53 Fno = 1.81 TTL = 5.43 ω(°) = 38.0Surface Data Surface Curvature Surface Refractive Abbe Focal Number iRadius r Distance d Index Nd Number νd Length (Object) Infinity Infinity 1 (Stop) Infinity −0.4000  2* 1.9232 (r1) 0.6548 (d1) 1.5445 (Nd1)55.98 (νd1) 4.65 (=f1)  3* 7.0407 (r2) 0.1131 (t1)  4* 4.0782 (r3)0.2200 (d2) 1.6709 (Nd2) 19.48 (νd2) −21.11 (=f2)  5* 3.0977 (r4) 0.4120(t2)  6* −42.2190 (r5) 0.3250 (d3) 1.6142 (Nd3) 25.58 (νd3) −42.76 (=f3) 7* 69.6969 (r6) 0.1461 (t3)  8* −2.9046 (r7) 0.2600 (d4) 1.6612 (Nd4)20.37 (νd4) −25.62 (=f4)  9* −3.6305 (r8) 0.0400 (t4) 10* 2.7322 (r9)0.4603 (d5) 1.5445 (Nd5) 55.98 (νd5) 17.76 (=f5) 11* 3.5818 (r10) 0.4331(t5) 12* 6.9868 (r11) 0.5346 (d6) 1.5348 (Nd6) 55.66 (νd6) 3.82 (=f6)13* −2.8146 (r12) 0.6082 (t6) 14* −6.3436 (r13) 0.3300 (d7) 1.5348 (Nd7)55.66 (νd7) −2.83 (=f7) 15* 2.0227 (r14) 0.1629 16 Infinity 0.21001.5630 51.30 17 Infinity 0.5928 (Image Plane) Infinity Lens group dataComposite Focal Length Entrance Pupil Diameter 1st lens-2nd lens 5.54(=f12) 2.455 (=EPD) 2nd lens-3rd lens −14.13 (=f23) 3rd lens-4th lens−16.13 (=f34) 6th lens-7th lens −86.93 (=f67) 5th lens-6th lens-7th lens15.81 (=f567) Aspheric Surface Data Second Surface Third Surface FourthSurface Fifth Surface Sixth Surface k 0.00000E+00 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 A4 −5.05180E−03  −1.13549E−01 −2.29143E−01  −1.63153E−01  −1.16018E−01  A6 1.60199E−02 1.36484E−012.82794E−01 1.96974E−01 2.41787E−03 A8 −1.48075E−02  −1.17273E−01 −2.14006E−01  −1.29398E−01  3.42193E−02 A10 −3.55903E−04  5.34006E−021.05013E−01 5.80941E−02 −4.24852E−03  A12 6.34621E−03 −1.00960E−02 −2.14225E−02  −8.09815E−03  −3.19474E−02  A14 −3.25195E−03 −6.82006E−04  0.00000E+00 0.00000E+00 1.69159E−02 A16 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 A18 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 A20 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 Seventh Surface EighthSurface Ninth Surface Tenth Surface Eleventh Surface k 0.00000E+000.00000E+00 0.00000E+00 −3.91420E+00  0.00000E+00 A4 −9.69961E−021.35181E−01 8.48016E−02 −1.17963E−01  −9.18598E−02  A6 −1.50415E−01 −4.59619E−01  −2.19494E−01  8.77711E−02 −1.42078E−02  A8 3.82625E−018.67009E−01 4.43263E−01 −2.32794E−02  5.74411E−02 A10 −3.45065E−01 −8.61132E−01  −4.94744E−01  −1.91674E−02  −4.42635E−02  A12 1.28926E−014.48441E−01 2.98852E−01 1.59276E−02 1.63110E−02 A14 −1.55071E−02 −1.14298E−01  −9.14102E−02  −4.21657E−03  −2.91122E−03  A16 0.00000E+001.08414E−02 1.11890E−02 3.80873E−04 2.00793E−04 A18 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 A20 0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 Twelfth SurfaceThirteenth Surface Fourteenth Surface Fifteenth Surface k 0.00000E+000.00000E+00 0.00000E+00 −9.43512E+00  A4 5.63840E−02 1.39612E−01−6.99805E−02  −5.76787E−02  A6 −6.96246E−02  −6.27864E−02  5.20049E−031.58162E−02 A8 3.10810E−02 1.04869E−02 5.45324E−03 −3.07035E−03  A10−1.11376E−02  4.03327E−04 −1.20350E−03  4.05778E−04 A12 2.59125E−03−2.78768E−04  6.27963E−05 −4.05449E−05  A14 −3.05899E−04  2.06182E−054.33067E−06 2.89866E−06 A16 1.38781E−05 0.00000E+00 −3.98827E−07 −9.75114E−08  A18 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 A200.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00

The imaging lens in Example 7 satisfies conditional expressions (1) to(18) as shown in Table 8.

FIG. 14 shows spherical aberration (mm), astigmatism (mm), anddistortion (%) of the imaging lens in Example 7. As shown in FIG. 14,each aberration is corrected excellently.

In table 8, values of conditional expressions (1) to (18) related to theExamples 1 to 7 are shown.

TABLE 8 Example1 Example2 Example3 Example4 Example5 Example6 Example7Conditional Nd1 1.5445 1.5445 1.5445 1.5445 1.5445 1.5445 1.5445Expression(1) Conditional f2/f −3.02 −5.10 −4.66 −4.51 −4.76 −6.24 −4.76Expression(2) Conditional t2/t3 0.68 0.82 0.84 0.94 0.98 0.78 2.82Expression(3) Conditional f567/f 3.38 4.04 4.25 3.96 3.70 4.42 3.56Expression(4) Conditional (r9 + r10)/ −5.07 −2.31 −7.02 −7.00 −7.45−0.87 −7.43 Expression(5) (r9 − r10) Conditional |f23|/f 2.23 2.10 2.242.24 2.35 2.60 3.18 Expression(6) Conditional t3/f 0.09 0.08 0.08 0.080.08 0.09 0.03 Expression(7) Conditional νd1 55.98 55.98 55.98 55.9855.98 55.98 55.98 Expression(8) Conditional νd2 20.37 19.48 19.48 20.3720.37 20.37 19.48 Expression(9) Conditional νd4 23.53 20.37 20.37 19.4819.48 19.48 20.37 Expression(10) Conditional νd5 55.98 55.98 55.98 55.9855.98 55.98 55.98 Expression(11) Conditional νd6 55.98 55.66 55.66 55.6655.66 55.66 55.66 Expression(12) Conditional νd7 55.66 55.66 55.66 55.6655.66 55.66 55.66 Expression(13) Conditional d1/f 0.14 0.14 0.15 0.130.15 0.15 0.15 Expression(14) Conditional f12/f 2.12 1.76 1.71 1.88 1.872.23 1.25 Expression(15) Conditional |f34|/f 5.11 7.15 9.71 7.33 7.385.09 3.64 Expression(16) Conditional f5/f 1.88 2.41 2.25 2.36 2.60 2.194.00 Expression(17) Conditional r1/r2 0.40 0.43 0.42 0.39 0.41 0.50 0.27Expression(18)

When the imaging lens according to the present invention is adopted to aproduct with the camera function, there is realized contribution to thelow-profileness and the low F-number of the camera and also highperformance thereof.

DESCRIPTION OF REFERENCE NUMERALS

-   STO: aperture stop,-   L1: first lens,-   L2: second lens,-   L3: third lens,-   L4: fourth lens,-   L5: fifth lens,-   L6: sixth lens,-   L7: seventh lens,-   ih: maximum image height,-   IR: filter, and-   IMG: image plane.

1-16. (canceled)
 17. An imaging lens comprising in order from an objectside to an image side, a first lens having positive refractive power, asecond lens, a third lens, a fourth lens, a fifth lens, a sixth lens,and a seventh lens, wherein said second lens has a convex surface facingthe object side near the optical axis, said fourth lens has a convexsurface facing the image side near the optical axis, and the followingconditional expressions (2), (16) and (17) are satisfied:−8.0<f2/f<−2.0  (2)2.5<|f34|/f<12.0  (16)1.7<f5/f<4.5  (17) where f: a focal length of the overall opticalsystem, f2: a focal length of the second lens, f5: a focal length of thefifth lens, and f34: a composite focal length of the third lens and thefourth lens.
 18. The imaging lens according to claim 17, wherein thefollowing conditional expression (3) is satisfied:0.3<t2/t3<3.3  (3) where t2: a distance along the optical axis from animage-side surface of the second lens to an object-side surface of thethird lens, and t3: a distance along the optical axis from an image-sidesurface of the third lens to an object-side surface of the fourth lens.19. The imaging lens according to claim 17, wherein the followingconditional expression (4) is satisfied:3.0<f567/f<10.0  (4) where f567: a composite focal length of the fifthlens, the sixth lens, and the seventh lens.
 20. The imaging lensaccording to claim 17, wherein the following conditional expression (5)is satisfied:−10.0<(r9+r10)/(r9−r10)<−0.5  (5) where r9: a paraxial curvature radiusof an object-side surface of the fifth lens, and r10: a paraxialcurvature radius of an image-side surface of the fifth lens.
 21. Theimaging lens according to claim 17, wherein the following conditionalexpression (6) is satisfied:1.0<|f23|/f<4.5  (6) where f23: a composite focal length of the secondlens and the third lens.
 22. The imaging lens according to claim 17,wherein the following conditional expression (7) is satisfied:0.01<t3/f<0.15  (7) where t3: a distance along the optical axis from animage-side surface of the third lens to an object-side surface of thefourth lens.
 23. The imaging lens according to claim 17, wherein thefollowing conditional expression (14) is satisfied:0.05<d1/f<0.30  (14) where d1: a thickness along the optical axis of thefirst lens.
 24. The imaging lens according to claim 17, wherein thefollowing conditional expression (15) is satisfied:1.0<f12/f<3.0  (15) where f12: a composite focal length of the firstlens and the second lens.
 25. The imaging lens according to claim 17,wherein the following conditional expression (18) is satisfied:0.1<r1/r2<0.7  (18) where r1: a paraxial curvature radius of anobject-side surface of the first lens, r2: a paraxial curvature radiusof an image-side surface of the first lens.
 26. An imaging lenscomprising in order from an object side to an image side, a first lenshaving positive refractive power, a second lens, a third lens, a fourthlens, a fifth lens having positive refractive power, a sixth lens havingpositive refractive power, and a seventh lens, wherein said second lenshas a convex surface facing the object side near the optical axis, saidfourth lens has a convex surface facing the image side near the opticalaxis, and the following conditional expressions (2) and (16) aresatisfied:−8.0<f2/f<−2.0  (2)2.5<|f34|/f<12.0  (16) where f: a focal length of the overall opticalsystem, f2: a focal length of the second lens, and f34: a compositefocal length of the third lens and the fourth lens.
 27. The imaging lensaccording to claim 26, wherein the following conditional expression (3)is satisfied:0.3<t2/t3<3.3  (3) where t2: a distance along the optical axis from animage-side surface of the second lens to an object-side surface of thethird lens, and t3: a distance along the optical axis from an image-sidesurface of the third lens to an object-side surface of the fourth lens.28. The imaging lens according to claim 26, wherein the followingconditional expression (4) is satisfied:3.0<f567/f<10.0  (4) where f567: a composite focal length of the fifthlens, the sixth lens, and the seventh lens.
 29. The imaging lensaccording to claim 26, wherein the following conditional expression (5)is satisfied:−10.0<(r9+r10)/(r9−r10)<−0.5  (5) where r9: a paraxial curvature radiusof an object-side surface of the fifth lens, and r10: a paraxialcurvature radius of an image-side surface of the fifth lens.
 30. Theimaging lens according to claim 26, wherein the following conditionalexpression (6) is satisfied:1.0<|f23|/f<4.5  (6) where f23: a composite focal length of the secondlens and the third lens.
 31. The imaging lens according to claim 26,wherein the following expression (7) is satisfied:0.01<t3/f<0.15  (7) where t3: a distance along the optical axis from animage-side surface of the third lens to an object-side surface of thefourth lens.
 32. The imaging lens according to claim 26, wherein thefollowing conditional expression (14) is satisfied:0.05<d1/f<0.30  (14) where d1: a thickness along the optical axis of thefirst lens.
 33. The imaging lens according to claim 26, wherein thefollowing conditional expression (15) is satisfied:1.0<f12/f<3.0  (15) where f12: a composite focal length of the firstlens and the second lens.
 34. The imaging lens according to claim 26,wherein the following conditional expression (17) is satisfied:1.7<f5/f<4.5  (17) where f5: a focal length of the fifth lens.
 35. Theimaging lens according to claim 26, wherein the following conditionalexpression (18) is satisfied:0.1<r1/r2<0.7  (18) where r1: a paraxial curvature radius of anobject-side surface of the first lens, and r2: a paraxial curvatureradius of an image-side surface of the first lens.